LOWER SILURIAN SYSTEM OF EASTERN MONT- 
GOMERY COUNTY, NEW YORK 
BY 
E. R. CUMINGS! 
Representatives of all the rocks of the typical American lower 
Silurian system, with the exception of the Chazy stage, may be seen 
within a radius of five miles of Amsterdam, in the eastern part of 
Montgomery county, New York. The city of Amsterdam is sit- 
uated on the easternmost of the series of uplifts that intersect the 
valley of the Mohawk river between Hoffman ferry and Littlefalls, 
all of which have thrust the lower rocks of the system through the 
upper. The present paper deals with the lower Silurian system as 
developed in the vicinity of Amsterdam in Perth, Amsterdam and 
Florida townships of Montgomery county, and Charlton, Glenville, 
Rotterdam, Princetown and Duanesburg townships of Schenectady 
county. In order that the following part of the paper may be less 
cumbered with footnotes’ a brief historic sketch and description of 
the system is here given in the following order: 
Historical sketch and review of previous work 
Calciferous sandrock. In his report on the Geological and agricul- 
tural survey of the district adjoming the Erie canal (1824) Prof. Eaton 
named the Calciferous sandrock, describing it as “an 
aggregate of quartzose sand and fine grains of carbonate of lime. . - 
The quartz is generally in the largest proportion ” (p. 32, 33). He 
states in another place that “the most perfect locality as well as 
the most accessible to those who travel the canal is Flint hill in 
Florida township and its continuation two or three miles west. In 
this locality we find dark brown and pearly hornstone, brown and 
1This thesis was submitted by Mr Cumings for honors in geology which were granted 
him by the faculty of Union college in June 1897. The accompanying geologic map 
of the Amsterdam sheet is the result of the work of Messrs Prosser, Cumings and 
Fisher.—0O. S. Prosser 
*Where volume and page references are given, the numbers are separated by @ 
colon; e. g. 3:21 means volume 3, page 21. Where reference is to “‘ part’’, pt 2, p. 401 
is the form used. 
